On 2016-06-17 13:31 +0200, to...@tuxteam.de wrote:
> OK. I've got one more hint. Reading through the open(2) man page
> (assuming it is really open what's failing on you -- what evidence
> do you have?), EAGAIN isn't listed among the possible errno values,
> but EWOULDBLOCK
>
> EWOULDBLOCK
> The O_NONBLOCK flag was specified, and an incompatible
> lease was held on the file (see fcntl(2)).
Thanks, I had only looked at EAGAIN.
> Now, on POSIX systems EWOULDBLOCK and EAGAIN could be one and the
> same.
On Linux, EWOULDBLOCK is #defined as EAGAIN in asm-generic/errno.h.
Also they are always the same in the glibc, regardless of the operating
system kernel.
> Lo and behold, a small test program on my box reveals that
> both at least translate to 'Resource temporarily unavailable':
>
> #include <stdio.h>
> #include <errno.h>
> #include <string.h>
>
> int main(int argc, char *argv[])
> {
> printf("EAGAIN is '%s'\n"
> "EWOULDBLOCK is '%s'\n",
> strerror(EAGAIN),
> strerror(EWOULDBLOCK));
> }
>
> ==>
>
> tomas@rasputin:~/prog/C$ ./errno
> EAGAIN is 'Resource temporarily unavailable'
> EWOULDBLOCK is 'Resource temporarily unavailable'
You don't have to write your own program, there is already an 'errno'
utility in the moreutils package. :-)
Cheers,
Sven
